Assessment of the Natural Frequency of the Sedimentary Cover in the Cologne Area (Germany) Using Noise Measurements

Abstract

Noise measurements were carried out at 381 sites in the Cologne area (Germany) using both short period and broad band sensors. The large number of data allowed both assesment of the influence of different sensors in the site response estimation and to compare the widely used H/V technique with the recently proposed Fourier Phase Spectral Method (FPSM). The results show that short period sensors are able to reliably retrieve site effects at frequencies well below their corner frequencies. Moreover, the H/V method should be preferred to the FPSM in determining the fundamental resonance frequency of soils. Finally, a map showing the resonance frequency distribution in the studied area was drawn using the results obtained applying the H/V technique. *

On the suitability of 1 s geophone for ambient noise measurements in the 0.1–20Hz frequency range: experimental outcomes

“…Unfortunately, with the increasing number of studies dealing with the application of this technique, there does not correspond an increasing number of studies focused on the capability of the used seismic instruments for properly recording seismic noise over the whole frequency band of interest in engineering seismology. Attempts in this direction were done, for example, by Mucciarelli (1998), who came to the important conclusion that accelerometers should be avoided, and by Parolai et al (2001) who compared the H/V spectral ratio results obtained by very popular 1 sec short-period seismometers with those derived by broad-band recordings.…”

Site-specific response spectra from the combination of microzonation with probabilistic seismic hazard assessment—An example for the Cologne (Germany) area

“…In an area mainly west of Cologne, nearly 400 sites have been investigated by Parolai et al [13,14,18]. Twenty of these, aligned on a nearly SW-NE oriented cross-section, are selected for this study (Fig.…”

“…The response of the sensors is flat between 1 and 40 Hz. All sensors have been calibrated and can be used to reliably analyse also frequencies lower than their natural one [13]. Data were recorded at 100 sps.…”

“…Within the DFNK project, PSHA were carried out taking into account the uncertainties in the input parameters [6,7]. Other studies provided detailed microzonation of the area [13,14].…”

Improving the spatial resolution of ground motion variability using earthquake and seismic noise data: the example of Bishkek (Kyrgyzstan)

“…Seismic noise recordings have recently become an important tool for site effects estimation (e.g., Bard, 1999;Parolai et al 2001;D'amico et al 2004), using both single stations and arrays to retrieve information about the fundamental resonance frequency of a site and the S-wave structure of the uppermost layers. Picozzi et al (2009) and Parolai et al (2010), for example, used single station noise measurements to infer resonance frequency maps of Istanbul, Turkey, and Bishkek, Kyrgyzstan, respectively.…”